Experimental Study on the Formation of Non-Metallic Inclusions Acting as Nuclei for Acicular Ferrite in HSLA Steels through Specific Deoxidation Practice and Defined Cooling Conditions

Abstract:

Specific types of non-metallic inclusions are known to act as heterogeneous nuclei for the formation of acicular ferrite, which provides excellent toughness. By increasing the amount of acicular ferrite in the microstructure, the properties of HSLA steels can be optimized significantly.Although the formation of acicular ferrite caused by heat treatments (thermomechanical treatments or welding) is quite well described in literature, there is less information to find about the formation of acicular ferrite immediately out of the liquid melt. Within the present study experiments on laboratory scale are carried out simulating the influence of cooling conditions and Ti-content on size, chemical composition and morphology of non-metallic inclusions and consequently on the amount of acicular ferrite. All experiments were carried out with a dipping test simulator enabling very well controllable cooling conditions. Optical microscopy in combination with special etching methods as well as SEM/EDS-analysis was used for microstructure and inclusion characterization.

• Periodical: Materials Science Forum (Volumes 783-786)
• Pages: 1079-1084
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.783-786.1079
• Online since: May 2014
• Authors: Susanne K. Michelic*, Denise Loder, Gregor Arth, Christian Bernhard
• Keywords: Acicular Ferrite, Heterogeneous Nucleation, HSLA Steel, Non-Metallic Inclusion

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